I've tried to run emerge --sync to fix it, but it still isn't available. I've also noticed that other packages available for the ppc-macos architecture aren't in my Portage tree. I think the problem is that SYNC= line, but I'm not sure where to go from here. Any help would be appreciated.

The new "prefix Portage" installation method maintains a separate "overlay" Portage tree. It is meant to replace the old arch installation method, where packages were selected based primarily on the arch keyword.